The present invention relates to methods of forming whey protein products having desirable physical properties, and the whey protein products so formed.
Milk whey protein is prepared by removing fat and casein from milk, and comprises xcex1-lactalbumin, xcex2-lactoglobulin and whey albumin. The main whey protein is xcex2-lactoglobulin (xcex2-lg), which constitutes about 50% of the total whey proteins. Large amounts of whey proteins are produced during the manufacturing of dairy products. The nutritional value of whey proteins makes them useful as food ingredients.
Whey proteins can be used as a protein source in desserts; however, it has been difficult to produce whey protein desserts with an acceptable texture without adding carbohydrate gelling agents (Mleko, Milchwissenshaft 52:262-265, 1997). The viscosity of whey protein dispersions is related to the size and shape of the protein molecules. Food proteins, especially whey proteins, are small ( less than 60 kDa) and more spherical in shape compared to carbohydrate hydrocolloids which are large (generally greater than 200 kDa) and rod-like. For coiled molecules, the viscosity is a function of the diameter of the coil and of the extent to which solvent can drain freely through the coil without becoming entrapped by hydrodynamic forces. For a homologous series of rods of constant diameter, the viscosity increases with molecular weight, which is proportional to the length (Cantor and Schimmel 1980, Biophysical Chemistry. Part II: Techniques for the study of biological structure and function, W. H. Freeman and Company, San Francisco, Calif.).
The functionality of a protein or polysaccharide is associated with specific chemical and physical properties of individual macromolecules, interactions with other ingredients, and the processing operations used in producing a given food. Food proteins and carbohydrate hydrocolloids differ in functionality. For example, the viscosity of carbohydrate hydrocolloids can be several hundred times higher than food proteins at the same concentration. To be acceptable for use in food products, whey protein products must have acceptable physical properties and acceptable mouth feel.
Accordingly, it is desirable to obtain whey protein dispersions with viscosities comparable to that of carbohydrate hydrocolloids.
In view of the foregoing, a first aspect of the present invention is a method of producing a whey protein product using a solution of at least about 2% whey proteins with a pH of at least about 8.0, which is heated and then cooled. The pH of the whey protein solution is adjusted to less than about pH 8.0, and the whey protein solution is heated in a second heating step to produce a whey protein product.
A second aspect of the present invention is a method of producing a whey protein product using a first solution of whey proteins having a pH of at least about 8.0, heating and then cooling this first solution, and then diluting the solution to provide a diluted whey protein solution. The pH of the diluted whey protein solution is adjusted to less than about 8.0, and it is heated in a second heating step to produce a whey protein product.
A further aspect of the present invention is a method of producing a whey protein product by providing a first solution of whey proteins having a concentration of about 4%. whey proteins and a pH of about 8.0, heating this solution in a first heating step at a temperature of at least about 75xc2x0 C. and then cooling to a temperature below the gellation point of the whey proteins. The resulting whey protein solution is diluted to a concentration of from about 2.5% to about 3.5% whey proteins and the pH is adjusted to about 7.0. The diluted whey protein solution is heated in a second heating step at a temperature of at least about 75xc2x0 C. to produce a whey protein product.
A further aspect of the present invention is a method of producing a whey protein product using a whey protein solution having a concentration of about 4% whey proteins and a pH of about 8.0, which is heated in a first heating step at a temperature of at least about 75xc2x0 C. and then cooled to a temperature below the gellation point of the whey proteins. The pH of the solution is adjusted to about 7.0, and it is heated in a second heating step at a temperature of at least about 75xc2x0 C. to produce a whey protein product.
A further aspect of the present invention is a whey protein dispersion having a viscosity of from about 200 to about 550 mPa s when measured at 50 l/s, having a concentration of whey proteins from about 2.0% to about 5.0%, and having an optical density of less than about 1.5 when measured at 630 nm.